1. Field of the Invention
The present invention relates to a time calculating apparatus, and more particularly to a sliding type apparatus that enables one to quickly and simultaneously display corresponding local standard time in all of the countries of the world, a number of overseas dependencies of various countries, and a large number of cities throughout the world.
2. Notice of Copyright
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
3. Description of the Related Art
As is well known, with the increasing use of intercontinental world travel, particularly with supersonic transportation being available, and the various telecommunications systems around the world, the different areas of the world are coming closer together. There have been attempts to satisfy the need to determine the exact time in the different areas of the world for people who are traveling or are interested in sending or using international forms of communication. Reliance is sometimes made on the use of multiple clocks, for example, in airline terminals, telegraph offices and the like, to show the various times around the world. This, however, is costly, and each clock must be calibrated from time to time. In other instances, electronic devices are used to read out the time in various parts of the world. However, this approach is usually not convenient for personal use since electronic devices are generally voluminous, expensive and/or cumbersome and sometimes even impossible to be transported from place to place.
As described in U.S. Pat. No. 445,392 it is known to construct a time chart from a map marked with meridians arranged apart at specified distances, where a movable strip is marked with the divisions of time corresponding with the time intervals between the meridians. However, this device is complicated to employ as it requires the user to have significant and specific geographical awareness and perform a complicated series of manipulations to determine the time in a specific country in a geographic region. Such manipulations render the device inefficient and generically impractical to use.
U.S. Pat. No. 3,807,629 teaches a slide rule for computing a time difference. However, this device is also complicated to use, requiring one to choose a relative geographic location and perform a series of adjustments to the device to calculate the time difference.
It is known from U.S. Pat. No. 1,607,560 to construct a time indicating device from a dial. However, due to its design, only a small number of localities can be displayed on its face, limiting its use. Furthermore, such a device is particularly cumbersome and not easily carried on one's person.
In U.S. Pat. No. 4,307,458 a watch for displaying multiple world times is disclosed. However, due to its structure, this device is limited in the number of localities which can be displayed. Furthermore, its design requires synchronization of its electrical elements, which can fail, rendering the device useless. Moreover, the use of electronic components increases the cost of the watch.
U.S. Pat. No. 5,303,956 is directed to a travel document folder having a time zone conversion chart rotatably mounted to one leaf of the folder. However, such design is inconvenient as its design inherently limits its content.
U.S. Pat. No. 5,054,008 teaches a device for determining the time anywhere in the world, relative to any selected geographical location. However, this device is complicated to use since it requires a significant awareness of geography. It also utilizes electronic components which make it costly to produce. Also, such electronic components may fail, rendering the device useless.
Finally, U.S. Pat. No. 2,463,758 relates to time indicating devices of the type with which the time of day or night at any place on the earth's surface can be calculated if a given time of day or night is known in a relative location. However, this device is complicated to use as it requires an extensive comprehension of geography. Furthermore, it requires the user to perform a number of complicated manipulations in order to achieve the desired result.
In summary, known devices for determining local standard time in various countries and areas around the world include some if not all of the following disadvantages: such devices are complicated to use; operation of these devices requires significant prior knowledge of geography and adequate mathematical capability plus time zone knowledge to calculate time zone differentials; many of the devices use electronic components which add to cost and create reliability issues; such devices are inefficient, impractical and not easily portable; the information content of the devices are limited by their design; and these devices are costly and not user friendly.
However, owing to the significant increase in international travel and communications and the globalization of world business, a great need exists for an efficient, compact and user-friendly time calculating apparatus.